Soon after 10.30am BST today, the Nobel committee will announce who has won the prize in physiology or medicine. For the winner, or winners, there will be congratulations, admiration and kudos. Not to mention the prize money of 10 million Swedish kronor (£934,000).

We will follow the announcement live and bring you comment and analysis from scientists in the field.

Today's award is followed by the physics prize on Tuesday morning and the chemistry prize on Wednesday. The two non-science prizes, for peace and economics, are revealed on Friday and Monday respectively. The date for the literature prize has not yet been announced.

As ever, the pundits have made their predictions for this year. The citation company, Thomson Reuters, names 18 scientists who might be honoured today. They include researchers whose work has focused on the immune system, treatments for chronic myeloid leukaemia and tissue engineering.

Other predictions for the prize recognise work on leptin, a hormone involved in body weight, and the development of induced pluripotent stem (iPS) cells for regenerative medicine.

Now it is time to hear what the committee has to say. We will stream the who ceremony here as soon as it begins.

We expect the live video stream of the announcements to be up and running in five or ten minutes.

Glitches are a something of a tradition for the Nobel prizes. The awards almost never happened because Alfred Nobel wrote his last will and testament without any help and introduced a number of flaws and legal problems that left it open to contest.

Part of the problem was that Nobel, who lived in Sweden, Russia, France and, finally, Italy, never claimed citizenship after leaving Sweden at the age of nine. The omission meant it was never clear which country's laws should apply to the will.

Nobel amassed assets in many countries and left the majority of his wealth to establish the prizes in physics, chemistry, medicine, literature and peace. Economics was added later.

The prizes were for "those who, during the preceding year, shall have conferred the greatest benefit on mankind."

10.18am: One prediction for the prize today is Shinya Yamanaka, who showed that it was possible to reprogramme adult cells into an embryonic stem cell-like form, and use these to regenerate other tissues.

But stem cells are still in their infancy so it may be too early for the Nobel committee to recognise the work as a major breakthrough. Remember, Robert Edwards, who pioneered IVF, received the award only last year.

10.22am: While we are waiting for the Nobel Foundation to sort out difficulties with live webstreaming...some brief background.

Alfred Nobel was born in October 1833 in Stockholm, but his family moved to St Petersburg when he was nine. His father ran an engineering firm that supplied the Tsar's armies with equipment.

Alfred was sent abroad to study chemical engineering. He spent time in Sweden, Germany, France and the US.

Alfred returned to Sweden with his father when the engineering firm went bust. There he focused on explosives, especially nitroglycerine. His younger brother, Emil, and four others, were killed in a nitroglycerine explosion in 1864.

This year's Nobel Laureates have revolutionized our understanding of the immune system by discovering key principles for its activation.

Scientists have long been searching for the gatekeepers of the immune response by which man and other animals defend themselves against attack by bacteria and other microorganisms. Bruce Beutler and Jules Hoffmann discovered receptor proteins that can recognize such microorganisms and activate innate immunity, the first step in the body's immune response. Ralph Steinman discovered the dendritic cells of the immune system and their unique capacity to activate and regulate adaptive immunity, the later stage of the immune response during which microorganisms are cleared from the body.

The discoveries of the three Nobel Laureates have revealed how the innate and adaptive phases of the immune response are activated and thereby provided novel insights into disease mechanisms. Their work has opened up new avenues for the development of prevention and therapy against infections, cancer, and inflammatory diseases.

10.42am: Some background on today's Nobel prize winners:

Bruce A. Beutler was born in 1957 in Chicago, USA. He received his MD from the University of Chicago in 1981 and worked as a scientist at Rockefeller University in New York and the University of Texas in Dallas, where he discovered the LPS receptor. Since 2000 he has been professor of genetics and immunology at The Scripps Research Institute, La Jolla, USA.

Jules A. Hoffmann was born in Echternach, Luxembourg in 1941. He studied at the University of Strasbourg in France, where he obtained his PhD in 1969. After postdoctoral training at the University of Marburg, Germany, he returned to Strasbourg, where he headed a research laboratory from 1974 to 2009. He has also served as director of the Institute for Molecular Cell Biology in Strasbourg and during 2007-2008 as President of the French National Academy of Sciences.

Ralph M. Steinman was born in 1943 in Montreal, Canada, where he studied biology and chemistry at McGill University. After studying medicine at Harvard Medical School in Boston, MA, USA, he received his MD in 1968. He has been affiliated with Rockefeller University in New York since 1970, has been professor of immunology at this institution since 1988, and is also director of its Center for Immunology and Immune Diseases.

Here is Ralph Steinman talking about dendritic cells after winning the Heineken prize.

11.08am: Jules Hoffmann made his pioneering discovery in 1996, when he and his team investigated how fruit flies combat infections. They used flies with mutations in several different genes including Toll, a gene previously found to be involved in the development of embryos.

When Hoffmann infected his fruit flies with bacteria or fungi, he discovered that Toll mutants died because they could not mount an effective defence. He was also able to conclude that the product of the Toll gene was involved in sensing pathogenic microorganisms and Toll activation was needed for successful defence against them.

11.12am: Bruce Beutler was searching for a "receptor" on cells that bound a substance produced by bacteria called lipopolysaccharide (LPS), which can cause septic shock, a life threatening condition that involves overstimulation of the immune system.

In 1998, Beutler and his team discovered that mice resistant to LPS had a mutation in a gene that was quite similar to the Toll gene of the fruit fly. This receptor, called TLR, turned out to be the receptor they were hunting.

The discoveries of Hoffmann and Beutler triggered an explosion of research in innate immunity.

11.15am: Ralph Steinman discovered, in 1973, a new cell type that he called the dendritic cell. He speculated that it could be important in the immune system and went on to show dendritic cells could activate T cells, which play a key role in adaptive immunity.

These findings were initially met with scepticism but further work by Steinman showed that dendritic cells have a unique capacity to activate T cells.

11.42am: Before today's prize announcement, the Wikipedia page of a Japanese stem cell researcher called Shinya Yamanaka was mistakenly updated to say he had won the Nobel – adding the award to his long list of achievements.

Yamanaka is certainly a contender for his work on reprogramming skin cells into stem cells, though the clinical applications of the research are far from clear at this point.

The false claim on Wikipedia was edited out within minutes.

12.20pm: Nobelprize.org has set up a page where you can send your greetings to this year's winners.

Remarkably, 60% of the 500 or so people who have responded so far say that they did.

From left to right, Jules A Hoffmann, Bruce A Beutler, and Ralph M Steinman, who have won the 2011 Nobel Prize in Physiology or Medicine. Photograph: Rockefeller University Press

1.21pm: In a press release, the Nobel Assembly at the Karolinska Institute sums up the medical importance of the work carried out by today's winners:

The discoveries that are awarded the 2011 Nobel Prize have provided novel insights into the activation and regulation of our immune system. They have made possible the development of new methods for preventing and treating disease, for instance with improved vaccines against infections and in attempts to stimulate the immune system to attack tumours. These discoveries also help us understand why the immune system can attack our own tissues, thus providing clues for novel treatment of inflammatory diseases.

The discoveries of these three Nobel Laureates is an excellent example of the impact we all get from investment in basic research, illustrating the benefits of understanding basic processes in the body and how long term they can impact clinical outcomes.

2.01pm: We're hearing from Rockefeller University that Ralph Steinman died three days ago. This presents a huge dilemma for the Nobel Assembly, because only living people can be awarded a Nobel prize. More to follow.

2.07pm:The university says Steinman passed away on Friday at the age of 68. He was diagnosed with pancreatic cancer four years ago, and his life was extended using a form of immunotherapy based on dendritic cells – which he himself had devised.

2.16pm: Rockefeller University president Marc Tessier-Lavigne says the university is delighted that the scientist's work has been recognised, "but the news is bittersweet, as we also learned this morning from Ralph's family that he passed a few days ago after a long battle with cancer. Our thoughts are with Ralph's wife, children and family."

Steinman's daughter, Alexis, said: "We are all so touched that our father's many years of hard work are being recognised with a Nobel Prize. He devoted his life to his work and his family, and he would be truly honoured."

2.35pm: The Nobel Assembly has told me by phone they are "shocked" at Steinman's death and will take a few days to consider whether the prize stands.

2.44pm: Nobel committee member Goran Hansson has told The Seattle Times the committee didn't know Steinman was dead when it chose him as a winner and is looking at its regulations.

Hanson said:

It is incredibly sad news … We can only regret that he didn't have the chance to receive the news he had won the Nobel Prize. Our thoughts are now with his family.

3.00pm: Nobel statutes don't allow posthumous awards unless a laureate dies after the announcement but before the award ceremony – which happened in 1996 when William Vickrey died a few days after it was announced he had won the economics Nobel. Steinman died three days ago.

4.13pm: In a phone conversation earlier this afternoon, Göran Hansson, secretary general of the Nobel committee, explained the sequence of events to me:

We never inform the winners in advance. I couldn't get through to Dr Steinman for obvious reasons, so I sent an email that was picked up by his daughter, who contacted the president of Rockefeller University. He then contacted us with the news.

Until 1974, a person could be awarded a prize posthumously if they had been nominated before February of the same year. This was the case for Erik Axel Karlfeldt, who won the literature Nobel in 1931, and Dag Hammarskjöld, who won the peace Nobel in 1961.

But the rules were changed in 1974. Hansson told me this appeared to be the first time since then that the prize had been awarded to someone who had died. "This is a unique situation we are facing," he said.

4.44pm: In an email, the president of the Royal Society and Nobel laureate, Sir Paul Nurse, writes: "This is a great tragedy. Ralph Steinman's work was ahead of its time and he waited too long for the Nobel prize. To die just days before its announcement is almost too much to bear. He will be remembered as one of the great immunologists of our time."

Tuesday 12.32pm: The Nobel Assembly has confirmed the Nobel prize for Ralph Steinman, despite his having died a few days before the announcement. The established rule is that the award cannot be given posthumously.

An interpretation of the purpose of this rule leads to the conclusion that Ralph Steinman shall be awarded the 2011 Nobel Prize in Physiology or Medicine. The purpose of the above-mentioned rule is to make it clear that the Nobel Prize shall not deliberately be awarded posthumously. However, the decision to award the Nobel Prize to Ralph Steinman was made in good faith, based on the assumption that the Nobel Laureate was alive.